Tubulation and lead-in construction



H. J. DAILEY TUBULATION AND LEAD-IN CONSTRUCTION oct. 19, 1954 Filed April 29, 1952 ILI y Pam M. Dn/LEX fra'.

Patented Oct. 19, 1954 FFICE TUBULATION AND LEAD-IN CONSTRUCTION Hampton J. Dailey, deceased, late of Verona, N. J.,

by Ruth M. Dailey, executrix, Verona,

N. J., as-

signor to Westinghouse Electric Corporation,

East Pittsburgh, vania Pa., a corporation of Pennsyl- Application April 29, 1952, Serial No. 284,912

Claims.

This invention relates to tubulation and leadin construction for use with electronic devices which have evacuated envelopes and electrodes therein requiring lead-in connections from the exterior of the envelopes.

In the design of electronic tubes, the tubulation or connection to the pumping system for evacuating the tubes has usually been of glass. This glass connection is fragile and extreme care is necessary to prevent the glass being stressed; otherwise fracture may result. When the tube is tipped off from the system adsorbed gas and Water vapor in the glass are unavoidably released into the tube, which is undesirable. The designing of connectionsbetween tube electrodes and external terminals which may be easily made without displacing the tube electrodes or placing strain on the glass seal is diiicult, with such connections usually being made by compression ttings such as bolts or eyelets or by spot welding. Compression joints are particularly unreliable and often lead to hot spotting or high resistance joints. Spot welding often leads to strains in the welded metals which often result in displaced electrodes.

An object of the present Vinvention is to provide an improved construction combining the tubulation and the lead-in connection for one of the electrodes.

Another object is to utilize the sealing of the tubulation to also secure the lead-in connection.

A further object of the invention is to provide a tubulation and lead-in construction which imposes no detrimental strains and yet is easily constructed and fully effective.

Other objects of the invention will appear to persons versed in the art to which it appertains as the description proceeds, both by direct reference thereto and by implication from the vcontext.

Referring to the accompanying drawing in which the numerals of reference indicate similar parts throughout the several views:

Figure l is an elevational section of an elec--v tronic device showing the invention incorporated therein;

Figure 2 is a longitudinal sectional view of the tubulation in process of fabrication;

Figure 3 is a cross-section on line III-III of Figure 2; and

Figure 4 is a longitudinal sectional View of a mcdied construction of lead-in connection.

In the specific embodiment of the invention illustrated in said drawing, there is shown, by way of example, an electron discharge device which (Cl. IWI-17.07)

comprises a glass or other ceramic bowl I0, here represented as part of an evacuated envelope, a metallic dome-like anode II being sealed in the rim thereof to constitute the complementary part of said envelope. For convenience of reference, said glass bowl IU will be considered as the base portion of the envelope. From the bottom of this bowl or base protrude a plurality of thimbles I2 of similar character and constituting prongs as a means for making exterior circuit connections and for support of the device. Protruding centrally from the bottom of the bowl or base, diiering somewhat from the other prongs I2 is a prong I3 wherein the present invention is exemplified and which will be described more in detail hereinafter.

The electron device includes therein a grid I4 and cathode I5, here shown of lamentary type,

and having a common center post I6 for support at their upper ends. The post is a conductor and external connection is made through the aforementioned central prong I3. The other prongs I2 have appropriate internal connections to the lower ends of the filaments and one to the grid.

Said nipple or prong I3 is fabricated to function initially as the exhaust tubulation and ultimately as an external terminal for a lead-in connection. As shown, said nipple comprises a copper or other suitable collar I'I having a rim thereof sealed to the margin of an opening I8 provided in the glass of bowl I. One mode of effecting a seal is to feather-edge said margin of the metal collar as it will respond to the expansion and contraction of the glass without developing cracks and leaks, and this type of seal has been arbitrarily selected for illustrative purposes. Below the feather edge portion of the collar, the same is shouldered inward as at I9 vto a smaller diameter of passageway, and below the shoulder is constituted as a depending hollow neck 2U.

Referring more particularly to Figures l to 3, a metal tube 2| is located within said neck and protrudes at both ends therefrom. This tube is preferably copper and of appropriate diameter to t in the neck 20 of collar II to which it is sealed by solder 22 or other suitable means. This uniting of the collar and tube is preferably performed before the collar is sealed to the glass bowl. A lead-in connection 23 extends from the cathode center post I6 downward into the tube 2I for a distance well below the shoulder I9 of the surrounding collar il, and by preference said lead-in connection is a fiat strip of copper, and

leaves adequate passageway within the tube for enabling the tube to function as an exhaust tubulation. The lower end of said tube may be connected to the pumping system and the electronic device thereby exhausted. When the pumping cycle is completed, tube 2i is pinched by a pair of pinching jaws 24. This pinching operation is preferably in a direction toward the fiat faces of the lead-in connection 23 contained within the tube. The pinching operation is accomplished with adequate Vpressure to obtain a cold welding of the flattened portion of the tube and with the lead-in connection so as to obtain a perfect vacuum-tight seal of the tube and electrical continuityT of tube and lead-in connection. The pressure applied to the pinching jaws is adequate to cold-flow the copper, or other material of which the tube and lead-in connection are composed, and to pinch-off the ends thereof, and is of the order of several thousand pounds. By this mode of sealing the tubulation, use of applied heat is avoided and thus avoids heat stresses in the glass and avoids generation or release within the device of gas and water vapor which are accompanying evils with sealing by applied heat. Furthermore, this mode of sealing assures perfect and permanent electrical contact between the tube and the lead-in connection.

After the tubulation has been sealed as above described, it is enclosed within a housing or thimble 25 making electrical contact therewith. This thimble is shown as shouldered to seat against the collar shoulder and iiared thereabove to provide a corona shield 28 around the featheredge seal of the collar and glass. Since the thimble, tube and collar are all metal, the thimble may have a filler 2l of solder therein at the part thereof below the shoulder thereby obtaining secure attachment and good electrical connection.

While the foregoing description has given an example of strip formation of the lead-in connection, the invention is equally applicable to tubular lead-in connection, this being included in the showing of Fig. 4. That modification provides a copper or other tube 2|a which has an opening 28 within the device so as to be usable as the exhaust tubulation, and this tube may extend upwardly in the device, in place of the strip 23 of Fig. 1, and constitute a lead-in connection to an electrode or part connected therewith. In this particular embodiment of Fig. 4, the neck a of collar l'la is shown extending along the tube far enough to be pinched off therewith thereby effecting rigid mechanical attachment and good electrical connection. The high pressure of the pinching jaws obtains a cold flow of the metals of both the tube and collar neck eiecting a weld therebetween as Well as a sealing closure of each. Exterior thimble and corona shield of Fig. l is equally applicable to the construction of Fig. 4.

What is claimed is:

1. An electron discharge device having a basal portion with an opening therein for exhaust purposes, a collar sealed to the margin of said opening, said collar having a sholuder and outwardly protruding neck therefrom and an exhaust tubulation in part within said collar and passing through and secured to said neck, the outer end of said exhaust tubulation having a cold-weld pinched closure.

2. An electron discharge device having a basal portion with an opening therein, a collar sealed to the margin of said opening, an exhaust tubulation in part within said collar and secured thereto, the outer end of said tubulation having a cold-weld pinched closure, and a thimble enclosing said outer end of the tubulation, said thimble being secured to said collar.

3. An electron discharge device having a basal portion with an opening therein, a collar sealed to the margin of said opening, an exhaust tubulation in part within said collar and secured thereto, the outer end of said tubulation having a cold-weld pinched closure, and a. thimble enclosing said outer end of the tubulation, said thimble being secured to said collar and said thimble having a corona shield extending therefrom toward and surrounding the sealed margin of said collar and opening.

4. A structural unit for an electron discharge device, comprising two metallic members of which one of said members is tubular and contains a part of the other, and said members being contiguous to each other for a substantial portion of the length of said tubular member and secured together at a pinched-off` end of the tubular member with the inner of said members within the said pinched-off end of the tubular' member.

5. A structural unit for an electron discharge device, comprising two metallic members of which one of said members is tubular and contains a part of the other, and said members being contiguous to each other for a substantial portion of the length of said tubularv member and secured together at a pinched-off end of the tubular member with the inner of said members within the said pinched-ofi end of the tubular member, and with the metal of the two members at said pinched-off end unified by a cold-welding thereof.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,132,175 Machlett Oct. 4, 1938 2,269,840 Anderson Jan. 13, 1942 2,454,572 Roovers Nov. 23, 1948 FOREIGN PATENTS Number Country y Date 119,966 Sweden Oct. 21, 1947 951,965 France Apr. 25, 1949 OTHER REFERENCES Plion, Abstract Ser. No. 55,478, published May 16, 1950. Y 

